Phytochemical investigation of Aloe pulcherrima roots and evaluation for its antibacterial and antiplasmodial activities

Abstract

Medicinal plants with documented traditional uses remain an important source for the treatment of a wide range of ailments. Evidence shows that majority of the Ethiopian population are still dependent on traditional medicine. Aloe pulcherrima Gilbert & Sebsebe is one of the endemic Aloe species traditionally used for the treatment of malaria and wound healing in central, Southern and Northern part of Ethiopia. The aim of the current study was, therefore, to isolate active compounds from roots of A. pulcherrima and evaluate for their antibacterial and antiplasmodial activities using standard test strains. Bioassay-guided sequential extraction and column chrom-atographic separation were employed for the isolation of bioactive pure compounds. The structures of the compounds were determined by 1D and 2D NMR spectro-scopic techniques. Disk diffusion method was employed to evaluate the antibacterial activities of the isolated compounds against four bacterial strains specifically (Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Escherichia coli ATCC 35218, Pseudomonas aeruginosa ATCC 27853). The malaria SYBR Green I-based in vitro assay technique was used for in vitro antiplasmodial activity evaluation of the compounds against chloroquine resistant (D6) and -sensitive (W2) strains of P. falciparum. Three compounds, chrysophanol, aloesaponarin I and aloesaponarin II were isolated from the acetone extracts of roots of A. pulcherrima. Evaluation of antibacterial activities revealed that aloesaponarin I and aloesaponarin II had significant activities against all the bacterial strains with inhibition zone diameters ranging from 18–27 mm as compared to the reference drug (gentamicin), which displayed inhibition zone diameter ranging between 20 mm (B. subtilis) and 25 mm (P. aeruginosa). The isolated compounds showed moderate in vitro antiplasmodial activity against both chloroquine resistant (W2) -sensitive (D6) strains. Isolation of chrysophanol, aloesaponarin I and aloesaponarin II from roots of A. pulcherrima is the first report of its kind. The finding could be used for further comprehensive evaluation of the isolated compounds for their antibacterial and antimalarial activities besides consideration of the same for potent drug development.

Chrysophanol: a review of its pharmacology, toxicity and pharmacokinetics

“…found that chrysophanol could inhibit the formation of biofilm in E. coli ATCC 25922 . In addition, chrysophanol showed an antileishmanial activity (IC 50 = 14.3 μg/ml), and antiplasmodial activity against both chloroquine‐resistant and chloroquine‐sensitive strains of P. falciparum (IC 50 = 7.80 and 20.13 μg/ml, respectively) . Caamalfuentes et al .…”

“…In addition, chrysophanol showed an antileishmanial activity (IC 50 = 14.3 lg/ml), and antiplasmodial activity against both chloroquine-resistant and chloroquine-sensitive strains of P. falciparum (IC 50 = 7.80 and 20.13 lg/ml, respectively). [41,42] Caamalfuentes et al [43] evaluated the activity of chrysophanol against G. intestinalis infection in CD-1 mice (IC 50 = 12.70 lg/ml). T1P1 cells were used as host cells for Japanese encephalitis virus (JEV), and the anti-JEV and virucidal activity with IC 50 of chrysophanol were 15.82 and 0.75 lg/ml, respectively.…”

Phytochemical-constituents, safety and efficacy of commonly used medicinal plants for the treatment of malaria in Ethiopia-a review

“…15 Both the pure compounds and latex produced the highest parasitaemia suppression at the middle dose suggested that 200mg/ kg body weight might be the optimal therapeutic dose in mice. 14 The other study by Dele et.al., 9 showed that the antiplasmodial activities of the two aloesaponarins from the root of A. pulcherrima were strong and promising against the chloroquine-sensitive strain and the antibacterial activity of aloesaponarin II was even greater than the reference drug (gentamicin 10μg) against B. subtilis.…”

“…7 In Ethiopia, artemether-lumefantrine replaced sulfadoxine-pyrimethamine (SP) in 2004 due to the increasing resistance of malaria to SP. 8,9 The emergence of artemisinin resistance has raised concerns that threaten the potency of existing anti malaria's and their therapeutic effectiveness of artemisinin which have been the drugs of choice is limited by a number of factors such as short half-life, neurotoxicity, and low solubility which affects their bioavailability. Traditional medicines are often more available, affordable and sometimes are perceived as more effective than conventional antimalarial drugs.…”

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“…[108,181] Aloin and aloe emodin in A. vera show antiplsomodial potential. [182] and A. pulcherrima leaves showed antiplasmodial activities [183] while its latex antimalarial activity [184] is used by Luhya Community of Kakamega East sub-County, Kenya; [185 ] A new compound, 9-dihydroxyl-2'-O-(Z)-cinnamoyl-7methoxy-aloesin (1), and eight known compounds (2-9) were isolated from Aloe vera tyrosinase inhibitory activity in Pepper mild mottle virus. [186] The extracts show better antimicrobial activity against bacterial strains as compared to fungal strains.…”